Porites Purple-Ring Disease

The condition you describe sounds, in general appearance, like the
Yellow-Band Disease currently evident in Montastraea "annularis" in the
Caribbean. There, the yellow band may be due simply to partial bleaching
of the sick coral. In the case of PPRD, I wonder if the pink/purple ring
is due to the revelation of animal pigments in the bleaching coral, rather
than any specific attribute of the disease. In which case, both could
result from the same pathogen! Or any of many..
Jeremy Woodley
Centre for Marine Sciences,
University of the West Indies (Mona),
Jamaica